Latch needle comprising a relieved latch shank

ABSTRACT

The improved latch needle ( 1 ) is provided with a latch ( 5 ) having a latch shaft ( 11 ) with side surfaces ( 21, 22 ), which are divided into surface areas ( 23, 24 ) that are offset against each other and/or are arranged at an angle to each other. As a result, the thickness of latch ( 5 ) measured in the direction of its rotational axis ( 27 ) is slightly larger than the thickness in the shaft region ( 43 ), particularly at a location ( 45 ) in the area of transition from the latch shaft ( 11 ) to the latch spoon ( 16 ). On the other hand, the location ( 43 )[sic] is close to the hook-side opening of the latch slot ( 6 ). By reducing the width, particularly in this region, the easy movement of latch ( 5 ) is ensured even if dust or dirt enter the latch slot ( 6 ) or are deposited on the side surfaces ( 21, 22 ).

[0001] The invention relates to a latch needle, in particular forknitting machines, having the features as listed in the preamble topatent claim 1.

[0002] Latch needles are used for different types of knitting machines.A latch needle is known, for example, from German Printed PatentSpecification 1113537. This latch needle has a needle body with a hookformed onto the end. A latch is positioned pivoting inside a latch slotformed near the hook. With its free end, the so-called latch spoon, thelatch can rest on the hook tip and thus close off the trappingclearance. From this closed position, the latch can pivot back to theupright position, in which the trapping clearance is freed. The pivotingmovement should be as easy as possible. Modern knitting machinesfrequently require needles that move easily. Hard to move needles knitunevenly and thus produce a poor loop picture.

[0003] The latches of some machines must fall back into the uprightposition as a result of their own weight. If this does not happenreliably, the danger exists that the latches come in contact with partsof the machine, e.g. the yarn-feed apron, and are bent as a result.

[0004] The easy movement of the latch can be achieved by increasing thelatch play. However, increasing the latch play worsens the latchguidance even if the needle is still new. With a further increase inwear, the latch guidance becomes less and less precise, thus reducingthe operational reliability.

[0005] Another problem resulting from increased latch play occurs if thelatch is positioned with rivets pressed out of the slot cheeks, asdisclosed in U.S. Pat. No. 1,991,140. For the positioning, the latchprovided with a bearing opening is inserted into the latch slot.Following this, sections of the slot cheeks are pressed or punchedtoward the inside with the aid of two plunging tools (engravers), suchthat these cheek portions enter the bearing opening in the latch andform a bearing rivet for the latch. This operation requires relativelylittle latch play. The latch forms a counter stop for the pressing orpunching operation, particularly with the region surrounding the bearingopening. If the latch is noticeably smaller than the latch slot, theslot cheeks are bent toward the inside during the punching operation,thus preventing the latch needle from being produced with the desiredquality.

[0006] Starting with this premise, it is the object of the invention toprovide a latch needle with a latch that is designed to move easily andis precisely guided.

[0007] This object is solved with a latch needle having the features asspecified in patent claim 1.

[0008] The latch needle according to the invention has a latchcomprising a latch spoon and a latch shaft, the side surface or surfacesof which are divided. A first surface area surrounds the bearing openingwhere it ensures a slight latch play on the side. The following secondsurface area permits a greater latch play, meaning the distance to theneighboring slot cheek is increased, thus reducing contact with the wallto small surface areas or omitting it completely. As a result, it ispossible to produce latch needles with latches that move extremelyeasily. For this, the surface area surrounding the bearing opening canbe designed such that the latch is guided with little play and thus veryprecisely. On the other hand, the following second surface area can beset back, thus reducing the thickness of the latch shaft by a few1000^(th) millimeters (for example 0.03 mm). During the opening andclosing of the latch, meaning the pivoting movement between closedposition and upright position, the second surface area that extendsalong the latch shaft is thus prevented from being wedged into the slotor from experiencing strong friction inside the slot. The set backsurface area contributes only slightly or not at all to the sideguidance of the latch. A functional separation between the surface areasexists. The first surface area surrounding the latch opening primarilyis responsible for the side guidance of the latch. This can possibly berecognized by the fact that the side play of the latch is respectivelythe same in the closed position or the upright position and an in anintermediate position. Having little latch play in the area of the rivetensures a good guidance of the latch inside the slot.

[0009] The insignificant latch play inside the slot in the region of theguide surface of the first surface area considerably facilitates theprocess of pressing out the rivet, meaning the pressing or punchingoperation during which sections of the cheek wall are pressed into thebearing opening of the latch. The insignificant play prevents the cheekwalls from being squeezed together when punching out the rivets and thusdeforming the needle. Especially precise needles can be produced as aresult.

[0010] On the other hand, the increased play between latch shaft andcheek wall reduces the danger of threads being wedged in, damaged or cutbetween latch and cheek (slot sidewall). In addition, it also reducesthe danger that fibers or dirt will enter the slot and result in ajamming of the latch.

[0011] Owing to the fact that the latch guidance is essentially assumedby the surface areas surrounding the latch, a noticeably larger spacingcan exist between the remaining latch flanks of the latch shaft and theslot cheeks. The difference between the thickness of the latch shaft inthe region of the latch hole and in the region of the latch head orlatch spoon can amount to several one-hundredth millimeters, withoutthis worsening the latch guidance.

[0012] Despite the improvement in the easy movement of the latch, thelatch is guided with such precision that the latch makes even bettercontact with the hook. As a result of the increased precision during theoperation of the needle, the wear between latch and hook can be reduced.In addition, the latch shaft does not make frictional contact over itscomplete length that is submerged in the slot, but only in the bearingregion on the slot cheek.

[0013] Both side surfaces of the latch shaft for the latch needle arepreferably designed identical, so that both side surfaces are dividedinto separate surface areas. The latch in that case is designed to besymmetrical to a center plane.

[0014] A line-shaped or strip-shaped separation or transition area isformed between the two separate surface areas. In other words, theseparation area, for example, takes the shape of a line, an edge or astep or forms a slightly curved transition area. The separation area ofone preferred embodiment is a step, which results in a large distancebetween cheek and surface area along the area recessed by the step. Thesurface area can be planar or can be curved in one or several directionsor can be structured. The same is true for the other surface areasurrounding the bearing opening, which can also be planar or otherwiseformed.

[0015] Additional advantageous details of embodiments of the inventionfollow from the description below, the drawing or the dependent claims.

[0016] The drawing shows exemplary embodiments of the invention, whichshow in:

[0017]FIG. 1 Details of a latch needle, shown as perspective andschematic representation.

[0018]FIG. 2 The latch needle according to FIG. 1, showing details in apartial sectional view from the side.

[0019]FIG. 3 The latch needle according to FIGS. 1 and 2, showingdetails in a partial sectional view from the top and on a differentscale.

[0020]FIG. 4 The latch for the latch needle according to FIGS. 1 to 3,showing a first embodiment in a view from the side.

[0021]FIG. 5 A modified embodiment of a latch for the latch needle inFIGS. 1 to 3, shown in a view from the side.

[0022]FIG. 6 A view from above of the latch needle shown in FIGS. 1 to3, with the latch in the central closing position.

[0023]FIG. 7 A schematic view from above of the latch needle accordingto FIG. 6, with the latch in the closed position and deflected to theside.

[0024]FIG. 1 shows a basic diagram of a latch needle 1. The latch needle1 has a needle body 2 with a hook 3 formed onto its free end. This hookends in a hook tip 4, which functions as counter stop and support for alatch 5 that is positioned pivoting on the needle body 2. A latch slot 6that is delimited by two cheeks 7, 8 is formed into the needle body 2for accommodating the latch 5. The cheeks 7, 8 are respectively leveland are arranged parallel to each other.

[0025] The latch 5 has a latch shaft 11, which projects with one end 12into the latch slot 6. FIG. 2 in particular shows that the end 12 isprovided with a latch opening 14 for positioning the latch 5. In aregion 45 at the opposite end 15, the latch shaft 11 changes over to alatch spoon 16, which is provided on the hook side with a recess 17(noucat).

[0026] A rivet 18, consisting of two rivet halves 18 a, 18 b, functionto position the latch 5 pivoting inside the latch slot 6. FIG. 3 showsthat these rivet halves are formed by pressing or punching wall sectionsout of the cheeks 7, 8 and into the latch opening 14.

[0027] The first embodiment of latch 5 is shown in FIG. 3. Thisembodiment has two side surfaces 21, 22 that extend over the twoopposite-arranged flanks of the latch shaft 11 from its end 12 to thelocation 45. The side surfaces 21, 22 are formed mirror-symmetrical to alongitudinal center plane 20, indicated with dash-dot line in FIG. 3.This is true at least for the preferred embodiment and otherwise alsoapplies to the remaining latch 5 and latch needle 1. The followingdescription of the side surface 21 therefore also applies to the sidesurface 22.

[0028] The side surface 21, in the same way as the side surface 22, isdivided into two surface areas 23, 24. The second surface area 23extends starting with the latch spoon 16 in the direction of latchopening 14 without reaching it. The surface area 23 can be a levelsurface. Alternatively, this surface area can also be curved in somesections, for example bent around a center axis of latch 5 or can berounded at its edges and in the end areas 25, 26 (FIG. 4).

[0029] The first surface area 24 can surround the latch opening 14 andcan thus be ring-shaped. The surface area 24 can also have a leveldesign for this. If necessary, the shape of the surface area 24 can alsobe interrupted, for example by indentations or indentations that extendin radial direction away from the latch opening 14, or the like. Whereasthe surface areas 24 of both side surfaces 21, 22 are preferablyoriented parallel to each other (FIG. 3), this is not absolutelynecessary for the surface areas 23. However, the embodiment according toFIG. 3 at least approximates this design, wherein the surface areas 23are spaced apart by a distance that is less by several 1000^(th)millimeter than the distance between the surface areas 24. The end 12 oflatch 5 thus forms a bearing device with the rivet 18 and the respectiveinsides of the cheeks 7, 8. This bearing device positions the latch 5with little play on the side, such that it can pivot around itsrotational axis 27, which simultaneously functions as center axis forthe rivet 18. The side (axial) play of latch 5 is illustrated in FIG. 3respectively with a gap 28, 29. This gap 28, 29 is smaller by several1000^(th) millimeter than a comparably larger gap 31, 21 that isspecified between the cheek 7, 8 and the respective surface area 23.While the gaps 28, 29 are preferably parallel gaps, the gaps 31, 32 canbe either parallel gaps or wedge-shaped gaps and can expand in thedirection of latch spoon 16. In that case, they reach the greatest widthin the area 45 at the end 15 of the latch shaft 11, at the transition tothe latch spoon 16.

[0030] The illustration in FIG. 4 shows that a separation area 33 isformed between the surfaces areas 23, 24, which is approximatelyline-shaped in this view from the side. FIG. 3 shows the area ofseparation in the form of a step 34, 35 having edges 36, 37, 38, 39,which can be slightly rounded if necessary. The step 34, 35 are only afew 1000^(th) to a few 100^(th) millimeters high but is neverthelessvisible with the naked eye.

[0031]FIG. 4 illustrates that the step 35 can be curved around the latchopening 14. If necessary, the step 35 can also be arranged along astraight line, as shown in FIG. 2. FIG. 3 shows that the step 35, 36 canhave a relatively steep design. If necessary, the step can also beformed by a ramp-like or embankment-type region, which creates a gradualtransition between the surface areas 23, 24.

[0032] A modified embodiment of latch 5 is shown in FIG. 5. Thedifference is in the separation area 33. Whereas this area wasrespectively designed as step 35 in the above-described embodiments,thus forming a z-shaped or s-shaped curved area in a view from above,the separation area 33 for the embodiment according to FIG. 5 is formedby a simple curved (arched) edge region 41. This region separates andconnects the surface areas 23, 24 and is visible on the side surface 21or 22 as an edge. If the edge area 41 is somewhat rounded, as indicatedin FIG. 5, it may not be visible immediately with the naked eye. Once itmakes contact with the surface areas 23, 24, it can be observed in themicroscope or measured with other means.

[0033] The latch needle 1 described so far shows improved knittingbehavior.

[0034]FIG. 6 illustrates that the latch 5 of latch needle 1 is guidedwith its end 12 inside the latch slot 6 and is positioned with the rivet18. The latch shaft 11 extends freely inside the latch slot 6 and, inthe ideal case, does not make contact with the cheeks 7, 8. At its end12, the latch 5 is guided with such precision that the latch spoon 16hits the hook 3 or the hook tip 4 with little center deviation. Theprecise guidance of the latch represents a wear reserve, meaning thateven if the latch play on the side increases with increasing wear, itremains within permissible tolerances.

[0035] The end 12 of latch 5 has a specific, slight play inside thelatch slot 6. As a result, the latch 5 can be deflected slightly to theside, as shown with arrow 42 in FIG. 7. The gap 31, 32 in that caseprevents that the respective side surface 21, 22 or the respectivesurface area 23 makes contact with its complete surface with the cheek7, 8. In the final analysis, this is achieved by designing the gap 31,32 to be larger than the respective gap 28, 29. The surface areas 23 atmost contact the cheeks 7, 8 in some sections or points. For theexemplary embodiment shown in FIG. 7, the surface area 23 and the cheek8 come only in contact only in one frontal location 43 for deflectingthe latch 5 to one side (in FIG. 7 toward the top). The spacing betweenthe surface area 23 and the cheek 8 is preserved at a distance theretoat location 44. It can also be achieved that the surface are 23 does notmake contact with the cheeks 7, 8.

[0036] The design of side surfaces 21, 22 of latch shaft 11 for latch 5,presented herein, permits an easy movement and precise positioning oflatch 5 inside the latch slot 6. The latch 5 moves easily even duringactual operations, meaning if fiber residues or dust enter the latchslot 6.

[0037] The improved latch needle 1 has a latch 5 with a latch shaft 11,the side surfaces 21, 22 of which are divided into the surface areas 23,24 that are arranged offset and/or at an angle to each other. As aresult, the latch 5 has a thickness, measured in the direction of itsrotational axis 27, which is somewhat greater than in the shaft region(43), particularly at a location 45 of the transitional area betweenlatch 11 and latch spoon 16. The location 43, on the other hand, ispositioned approximately at the hook-side opening of the latch slot 6.By reducing the width, especially in this region, the easy movement oflatch 5 is ensured even if dust or dirt enter the latch slot 6 or aredeposited on the side surfaces 21, 22.

1. A latch needle (1), in particular for knitting machines, said needlecomprising a needle body (2) with a latch slot (6) formed therein, whichis delimited by two opposite arranged cheeks or slot side walls (7, 8),a latch (5) with latch shaft (11) that extends inside the latch slot (6)and has two side surfaces (21, 22) and a latch opening (14) and ispositioned so as to pivot with the aid of a bearing device (18) insidethe latch slot (6), characterized in that at least one of the sidesurfaces (21, 22) are divided into separate surface areas (23, 24), oneof which is located next to the latch opening (14) and the other oneextends on the side along the latch shaft (11) and away from the latchopening (14) and that the distance between the side surfaces (21) at alocation (43 and/or 45) that is removed from the bearing device is lessthan the distance between the regions adjacent to the latch opening(14).
 2. A latch needle according to claim 1, characterized in that bothside surfaces (21, 22) of the latch shaft (11) of latch needle (1) aredivided into separate surface areas (23, 24).
 3. A latch needleaccording to claim 1, characterized in that a separation area (33) inthe shape of a line or strip is formed between the surface areas (23,24) in order to separate these areas.
 4. A latch needle according toclaim 3, characterized in that the separation area (33) extendscrosswise over the side surfaces.
 5. A latch needle according to claim1, characterized in that a step (34, 35) as separation areas (33) isformed between both surface areas (23, 24) in order to separate theseareas.
 6. A latch needle according to claim 1, characterized in that anedge area (41) as separation area (33) is formed between both surfaceareas (23, 24) in order to separate these areas.
 7. A latch needleaccording to claim 6, characterized in that the edge area (41) isrounded.
 8. A latch needle according to claim 1, characterized in that avisible edge is formed as separation area (33) between the surface areas(23, 24) in order to separate these areas.
 9. A latch needle accordingto claim 3, characterized in that the separation area (33) is designedto be straight.
 10. A latch needle according to claim 1, characterizedin that the separation area (33) is designed to be curved.